Process of treating sulphur-containing oils



Patented Jan. 20, 1931 UNITED STATES PATENT OFFICE.-

HERBERT G. I. FISCHER, OI WESTIIELD, AND WILLIAM J. ADDEMS, OF ELIZABETH,

' NEW JERSIH, ASSIGNOBS TO STANDARD OIL DEVELQPKENT COMPANY, A. CORPORA- TION OF DELAWARE PROCESS OF TREATING SULPHUR-CONTAINING 0118 lo Drawing. Application filed 8, 1926. Serial Io. 107,18 7.

This invention relates to improvements in as it is, without any revivifying or recondi methods for reducing or eliminating the tioniug. a 4 sul hur content of hydrocarbon oils, or for Although the oil is sweet, or substantially ma g the sulphur content unobjectionable. so, after the treatment described, the sulphur 5 The invention has particular reference to the content may be too high; the oil may not sweeteningof kerosene and will 'be' depass the standard sulphur-content-tests; An scribed for illustration in this connection. important feature of our invention is the However, the process may be applied also distillation of the oil under regulated conto naphthas and other oils. or ditionsto free it from the sulphur com- It is well known that the sourness of unds. The polysulfids'are relatively high kerosene is caused by the presence in it of oiling as compared with the mercaptans and organic sulphur compounds, chiefly mermay be. separated from the oil by distilling captans, of the type -R.HS. According to it at temperatures in general not exceeding usual practice, sour "oils are sweetened by about 320 F. At higher temperatures the 15 treatment with doctorsolution? (an aqueous polysulfids decompose, producing volatile solution of sodium plumbite) with or with mercaptans and hydrogen sulfid, with re-' out the addition of elementary sulphur. Oils sulting contamination of the distilled oil. containing a high percentage of sulphur in With most stocks it is necessary to distill organic combination, for example kerosene under vacuum to' volatilize the oil below the it from Reagan crude, when treated according temperature stated. A naphtha fraction to prior practice require a very large amount may be takenofi. with fireand steam distillaof doctor solution, and the expense of sweettion, vacuum being applied to obtain the ening by means of this reagent is practically kerosene fraction. The residue in the still prohibitive. is a conc'entrateof the polysulfids. The dis- 25 We have found that sour oils of th type tillate is oilof very low sulphur content. It referred to maybe successfully and econommay in some cases be slightly sour, in which ically treated by the following method: The case a light treatment with doctor solution oil is mixed in an agitator of suitable type, suflices to sweeten the oil. However, if care either batch or continuous, with elementary is taken to sweeten the oil completely before surphur, a 15 B. solution of sodium hydistillation, the distillate will be Sweetdroxid, and lead sulfid. The agitation may The following example giving weights 'of be by air blowing at ordinary temperature. the reagents used is illustrative: 2020 lbs. of The amount of sulphur to be added'is des p u pr f r b y as flowers of ph termined primarily by the quantity of me u and 1100 lbs. 0f lead Slllfid wereaddedto 5500 captan sulphur present in the oil. Enough l kerosene from Reagan l an elementary sulphur .is added to convert the jlgltaton Then 2500 galsof sodlum mercaptans int'o polysulfids, which may be of the type R 5 Oxygen derived from the air used for agitation or fromany other suitable source, is desirablebut not necessary.

Our experiments have shown that the oil is sweetened by adding sulphur'in amount about equal to one-half the mercaptanv sul-' phur. The added 'sulphufiwhichis apparently fixed in organic combination, does not make the oil corrosive. The sodium hydroxid and lead'sulfidappear to act catalyhydroxid solution was supplied to the agitator. The charge was agitated for about 1% hours at ordinary temperature, allowed to settle, and was then drawn off and distilled as above described, taking overhead 91% with a loss of 1% and leaving 8%-in the still.

The kerosene stock had an initial total sulphur content of 0.264%, of which 82% was mercaptan sulphur. The kerosene distillate was sweet, as shown by the doctor test. The

sweetened stock before distillation a sulphur content of 0.372% and was nontically. The lead may be separated corrosive, as shown by the copper striptest 50 after the treatment 1s finished and reused for one hour at 212 F. The kerosene after distillation had a sulphur content of only 0.108%. Its original color and color stability were excellent. It Showed a loss of only' two color shades (Saybolt refined oil colorimeter) after heating to 212 F. for 16 hours. The kerosene gave no corrosion on the cop-per strip test for one hour at 212 F. The odor of the kerosene was good and was not affected by heating. The bottoms in the still had a sulphur content of 3.15%.

Acid treatment is not ordinarily necessary when proceeding according to our process, but is frequently beneficial. The polysulfids formed are quite soluble in sulphuric acid and are not substantially decomposed by it. The stock may therefore be acid treated before distillation, if desired. As an example, kerosene from Reagan crude was treated with 6 lbs. of restored 66 B. sulphuric acid per bbl. of kerosene after the sweetening treat. This lowered the sulphur content of the stock to 0.342%. After distillation, conducted under substantially the same conditions as before, the kerosene distillate (90.5% of the charge) had a sulphur content of only 0.066%. It had a color and color stability better in some respects than when the acid treatment was omitted. The kerosene was only slightly sour after distillation, requiring 25 lbs. of lead oxid to sweeten 5500 bbls.

of oil. The bottoms in the still had a sulphur content of 3.8%.

It is sometimes desirable to add the sulphur in the form of an aqueous solution of an alkali metal sulfid or polysulfid, especially sodium sulfid. Solutions of sulphur in hydrocarbon oils are also suitable. Preformed lead sulfid, alkali, and oxygen are used as Care should be taken that th sulphur added,

together with the elementary sulphur already present in the oil .is not in excess of the amount of sulphur but is sweet and non-' corrosive. If the percentage of total sulphur at the completion of the reaction is.within permissible limits, the distillation may be omitted.

In some cases we may form the lead sulfid of our invention may be varied widely. A

reasonably large amount is necessary to secure reaction of the desired rapidity;

Instead of lead sulfid we may use other heavy metal 'sulfids having equivalent properties for this reaction, especially cupric or cuprous It will be understood that the foregoing examples are illustrative and that various changes ma be made within the scope of the appended c aims, in which it is our intention to claim all novelty inherent in the invention as broadly as the prior art permits.

We claim 1'. Process of treating hydrocarbons contaimng mercaptans, comprisin bringing the hydrocarbons into contact wit a preformed heavy metal sulfid, an alkali, and sulphur in amount 'suflicient to convert at least the greater part of the mercaptans into polysulfids.

2. Process of treating petroleum oil containing mercaptans, comprising agitating the oil with preformed lead sulfid, sodium hydroxid, and sulphur in amount sufficient to convert the mercaptans' into polysulfids.

- 3. Process of treating a sour petroleum distillate, comprising agitating the distillate with sulphur in the presence of a heavy metal sulfid and an alkali, whereby sweet sulphur compounds are formed, distilling the distillate below a temperature at which the sweet sulphur compounds are substantially removed from the distillate, and taking off a distillate substantiallyfree from sulphur.

4. Process of treating a sour petroleum distillate, comprising agitating the distillate with sul hur in the presence of preformed lead su d and a water solution of sodium hydroxid, whereby sweet sulphur compounds are formed, distilling the distillate below a temperature at which the sweet sulphur compounds are substantiall removed from the distillate, and taking oil a distillate substantially free from sul hurt 1 5. Process acco g to claim 4, in which the substantially sulphur-free distillate is given a final light treatment with doctor solution.

6. Process 'of sweetening petroleum distillates containing sour sulphur compounds, comprising agitating the distillate with sulphur in the presence of preformed lead sulfid and an alkali, whereby the sour compounds are converted into compounds of higher boildistillate, comprising agitating the distillate and drawing oil the acid treated distillate,

ingpoint, distilling the distillate at a temperature not substantially above 320 F., and taking off a distillate substantially free from sulphur.

5 7. Process of treating petroleum hydrocarbons containing sour sulphur compounds of the type of mercaptans, comprising mixing the hydrocarbons with sulphur in the presence of lead sulfid and an alkali, the total 10 amount of lead in the mixture being insuflicient to directl convert more than a small proportion of t e mercaptans into lead mercaptides'. I

8. Process of treating a sour petroleum with sulphur in the presence of lead sulfid and a water solution of sodium hydroxid, whereby sweet sulphur compounds are formed; acid treating the distillate, settling and distilling the distillate at a temperature below that at which the sweet sulphur compounds are substantially removed from the distillate. v

9. In the treating of petroleum hydrocarbons containing sour sulphur compounds of the type of mercaptans, the improvement that comprises mixing the hydrocarbons with preformed lead sulfid, alkali, and sulphur in amount about equivalent to one-half the sulphur content of the mercaptans, whereby polysulfids are formed.

10. Process according to claim 9, in which the mixing is by blowing with air.

11. Process according to claim 9, in which the treated 'oil is distilled at a temperature below that at which the polysulfids decompose, whereby they are concentrated in the .distillation residue.

40 12. Process of treating sour petroleum oil, comprising agitating the oil with sulphur in the presence of preformed lead sulfid, sodium hydroxide, and oxygen.

13. Process of treating sour petroleum oil comprising addin to the oil" a preformed heavy metal sulfi sulphur, and sodium hydroxide, and agitating the oil by blowing with air.

' HERBERT G. M. FISCHER. WILLIAM J ADDEMS. 

